1. Field of the Invention
The present invention relates to remote copy using a journal.
2. Description of the Related Art
For example, Patent Document 1 discloses a technique in which a primary storage system receives write data from a primary host computer and reports to the primary host computer that the receipt of write data has been completed immediately after the write data was received. Thereafter, the host computer reads a copy of the write data from the primary storage system. The write data is associated with a write time which is a time at which a write request for the write data is issued, and, when the write data is read by the primary host computer, the write time is passed to the primary host computer. In addition, the primary host computer sends the write data and the write time to a secondary host computer. Upon receiving the write data and the write time, the secondary host computer writes information such as the write time in a control volume of a secondary storage system and further writes the write data in the secondary storage system in a sequence of write time by referring to the write time associated with or corresponding to the write data.    [Patent Document 1] Europe Patent Application Publication No. 0672985